Dentistry.



Patented Oct. 2, I900. A. P. JOHNSON.

DENTISTRY. (Application filed Aug. 10, 1900.)

(No Model.)

WITNESS a QM A 0HNEYS 1 o attained.

UNITED STATES.

AUGUST P. JOHNSON,

PATENT OFFICE.

OF ADA, MINNESOTA.

DENTISTRY."

SPECIFICATION forming part of Letters Patent No. 659.196. dated October-.2, 1900.

I Application filed August 10, 1900. Serial No. 26.600- (No model.) i i To all whom it may concern;

Be itkuown that I, A GUsr P. JOHNSON, of Ada, in the county of Norman andSiate of Minnesota, Improvement in Dentistry,"of which the following is a specif cation. r

My invention is an improvement iu the con! struction and attachment of pivot-teeth, whereby various The construction, arrangement, and combination of parts are ashereiuafter described,

and shown in accompanying dyawings, in which-- V Figui'e l is a perspective view,includingthe root of anatnral' tooth, an artificial to0th,'a post oranchor for the latter, and a' cap. Fig, 2 is an in'clo sedlongitud-inal section showing the aforesaid parts connected asin use. Figs.

2o 3 and 4 -are cross-sections on lines 3 3 and 4 4,

' to the cap shown in Fig.

0 and also 3 5 constructed integrally;

respectively, of-Fig. 2. Fig. 5isaperspective view of a modified cap. Fig. 6 is a'perspective view of. .a bandwhich in practice is secured 5. Fig. 7 is a side view of an anchor, post, or pivot. ,Fig. Sis an end view'of the anchor or post shown in Fig; 7. Fig. 9 shows a modification of the twist.

In Figs.- 1 and 2jthe natural root 1 .is shown bored longitudinally, the bore 2 being tapered I circular in cross-section at every point. The base -3 of the root 1 is ground conoidal or symmetrically-rounded, and the gold cap 4 to be applied thereto has a like shape. The cap 4 has the usual band or flange but in Fig. 5 I 'show a plain or flangeless cap 5, the same having a simple concavo-convex form. Fig 6) is' to'be fitted to the root by the operator and then soldered to the edge of the cap 5*. 'Thi's method is particularly applicable and advantageous when the end of the root is of abnormal shape.- The porcelain artificial --tooth'orcrown 7 has aconoi'dal or symmetricallyrounded] cavityv 8, which corresponds 5 exactly to the cap 4on5, and will hence fit 5b closely and accurately the crown" thereon,however' adjustedfon the base .3 of root 1;. This conical constructionof the cap 4 on o and the cavity Sfof; crown 7 has the i great advantage that the cap will always fit I and the end of: the,'root 1 can always be ground to have invented .a new and useful important advantages are.

A band 6 (see ,make a like fit and tight joint, leaving a minimum quantity of cement between the crown and root-to dissolve, out, yet suflicient is presem to attain the result of greater security of connection or attachment of the crown. The anchor or post is baked Or fused into the allporcelain crown in the process of manufacture; and thus both are sold as one article.

and anchor and is soldered to the anchor when-the' crown is ready tobe secured tothe root. Thus the gold cap, being in the first-in- ;stance free or unattached to the post and crown 7, may be accurately adjusted and fitted to the,root-.base 2 and is then applied to the post and in the caviiyio'f the crown and secured-by soldering it to the former.. The whole appliancethe'crown=,- post, a'nd capis then applied to the root 1 and forced into "place, a small quantity of cement being first placed in the cap, so that a material will be between the cap and rootbase. 2. The hole in the cap may be enlarged y shifting or adjustment of the crownand cap relative to each other. 4

It is apparent that the conoidal shape and enables the crown to be set at an angle to the root,'instead of inv alinement with it, without afiecting the accuracy of. fit or joint and that the cap and crown being made and furnished to the operatorin such form much timeis saved to. the latter, while a further advantage is attained by using a porcelain crown having no and its artificiality is not case of crowns whose metal back is often dis- It has thus all the advantages of the wellknown Richmond crown without any of its disadvantages.

The anchor or post has the following peculiarities of construction and attachment and relation to other parts. It is ta ered and grooved on three sides throughout ts length, and two-thirds of its distal portion or the portion occupying two; thirds of the length of The cap is made and maybe sold separate or unattached, and it is to be fittedon the end,

thin layer of such the symmetrical relation of the parts described closed by translucency'of the face portion.

3 of the root before being applied to the crown .the dentist when required to allow any metal back, since such crown is less liable to crack or be defaced by use, is much stronger, exposed, as in the LII bore 2 in theroot 1 is twisted forthe purpose incisors of affording a very secure hold in the latter In Figs. 1, 2, and 7 the upper portion 9 of the post is shown twisted, and in Fig. 0 the central portion 9" is twisted. Thus in each case the lower portion of the post retains itsv regular shape or form. It is held firmly in the ceni'enting material and cannot turn or rotate, as otherscrews have done. The notches or circumferential recesses with which posts are often provided greatly weaken them, whereas my 'post is greatly strengthened by of short bitesv or Where the lower VVhat I claim is' 1. The improved dental attachment prising the crown orart-ilicial tooth having a symmetrical conoidal depression or. cavity, the post or anchor baked in said crown and fixed in the center of said cavity, the convex metal cap, of the crown and post and having a central opening adapted to receive the post and allow adjustment therein, its convexity being syml metrical and having the same degree of cured to fit in the same, whatever he the adjustment of the crown, as and for the purpose shown and described. At 2-. An anchor or post for artificial toothcrowns which is tapered, twisted, and also grooved longitudinally, substantially 'as shown and described.

'3. An anchor or post for artificial tooth.- crowns which is grooved throughout its length, and tapered and twisted in its distal portion,substantially as shown and described.

AUGUST P, JOHNSON,

fit the bore 2 accurately. In other words, all the points on its surface in any cross-section that come in contactwith the bore areequidistant from the center of the post.

The base of the post is slanted or beveled at 10, so that the operator may grind olf a'conside'rable portion of the back of,the crown Witnesses: without exposing the adjacent corner of the Mrs. G. E. TAYLOR, post Such grinding is required in the case HORACE W. EATON.

coinmade separately or independently vature as the said cavity, whereby it is adapt- "infringe on the inner side of the upper ones. 

